Robin Williams last seen alive in his home at 10 p.m. Sunday, body discovered about noon Monday

Actor Robin Williams was last seen alive inside his home late Sunday night before his body was discovered just before noon Monday, the Marin County Sheriff’s Office said.

Authorities are expected to release further details about the Oscar-winning actor's death at a news conference Tuesday, but in a statement, they said Williams was last seen alive inside his Tiburon home at 10 p.m. Sunday. They did not specify by whom or under what circumstances.

The Marin County Sheriff's Office said he appeared to have committed suicide, with asphyxiation a possible cause of death. He was pronounced dead at the scene.

The actor had been battling "severe depression of late," his publicist Mara Buxbaum said.

"This is a tragic and sudden loss. The family respectfully asks for their privacy as they grieve during this very difficult time," Buxbaum said.

The news of the beloved 63-year-old actor’s death rocked the nation Monday. TV channels broke into their usual programming to make the announcement, and within minutes, Williams dominated online trending topics. President Obama noted his passing.

Marin County sheriff's officials said comedian Robin Williams committed suicide by hanging himself with a belt in his bedroom, where he was found dead Monday.

Marin County sheriff's officials said comedian Robin Williams committed suicide by hanging himself with a belt in his bedroom, where he was found dead Monday.

Born in Chicago in 1951, Williams was accepted into John Houseman’s acting program at Juilliard along with Christopher Reeve, who became a lifelong friend.

Dubbed “the funniest man alive” by Entertainment Weekly in 1997, Williams brought audiences hours of laughter, putting his imaginative spin on characters in film and television. He was lauded for his serious roles as well, winning a best supporting actor Oscar for his performance as Sean Maguire, the therapist who counsels Matt Damon’s math genius in “Good Will Hunting” (1997). He also received nominations for “The Fisher King” (1991), “Dead Poets Society” (1989) and “Good Morning, Vietnam” (1987).

Asphyxia from an apparent suicide is what officials are initially saying is the cause of death for 63-year-old comedian Robin Williams, ahead of an official coroner's report.

Asphyxia from an apparent suicide is what officials are initially saying is the cause of death for 63-year-old comedian Robin Williams, ahead of an official coroner's report.

Kelly Cook, 50, who lives down the street, called the actor "brilliant," as well as "really quiet and private." An avid cyclist, he was often seen riding the Paradise loop, which hugs the Tiburon peninsula.

By Tuesday morning, flowers, candles and memorabilia had piled onto Williams' star on the Hollywood Walk of Fame. Williams had received the last star in front of TCL Chinese Theatre, previously known as Grauman’s Chinese Theatre.

Tourists left messages on paper, magazine covers with his face or pictures of Williams from the innumerable charity events he attended over the years.